3D Printing
Also: additive manufacturing, AM, rapid prototyping, industrial 3D printing, 3D printing service, additive
3D printing builds parts layer by layer from CAD. Choosing between FDM, SLA, SLS/MJF and metal powder bed fusion by material, tolerance, finish and cost.
771 3D printing companies in the Noramark directory
Every 3D printing process slices the CAD model into thin layers and builds the part one layer at a time, with no tooling and no fixtures. The first part costs about the same as the hundredth, internal channels, lattices and consolidated assemblies can be built in one piece, and a STEP file becomes a part in days. The price is lower accuracy, rougher surfaces and more variation in properties than a machined or molded part, and a cost per part that barely falls with quantity.
Four families cover most U.S. job-shop work. FDM extrudes thermoplastic filament: the cheapest and largest prints, and the common route to printed Ultem and PEEK, but with visible layer lines and weak bonds between layers. SLA cures liquid resin with a laser or projector: the finest detail and smoothest surface, for cosmetic and clear prototypes and casting patterns, but the resins are brittle and age in sunlight. SLS and HP Multi Jet Fusion (MJF) fuse nylon powder: tough functional parts with no supports, economical into the low thousands. Metal laser powder bed fusion (LPBF, often sold as DMLS) melts metal powder into dense titanium, stainless, nickel alloy and aluminum parts, at the highest cost and with a post-processing chain of stress relief, support removal, HIP and machining.
Choose by what the part has to do. For a look-and-feel model, SLA. For a fixture or a large, cheap prototype, FDM. For a working plastic part in quantities from one to a few thousand, SLS or MJF. For a metal part with internal passages, or a shape that cannot be machined or cast economically, LPBF. Small parts hold about ±0.1-0.2 mm (±0.004-0.008") in SLA and metal and ±0.2-0.3 mm (±0.008-0.012") in FDM, SLS and MJF; anything tighter is machined after printing. Once volumes reach the thousands, injection molding, die casting or investment casting usually take over.
At a glance
| Typical tolerances | Standard, small parts: SLA ±0.1 mm (±0.004"); metal LPBF ±0.1-0.2 mm (±0.004-0.008") after stress relief; industrial FDM ±0.13-0.25 mm (±0.005-0.010"); SLS and MJF ±0.3 mm (±0.012"). Add roughly 0.1-0.3% of the dimension on larger parts. With care, ±0.05 mm (±0.002") on small SLA features; ±0.025 mm (±0.001") only on features machined after printing. |
|---|---|
| Size limits | Metal LPBF: commonly 250 x 250 x 300 mm (10 x 10 x 12"), 400 mm (16") cubes at larger shops, 600 mm (24") class machines at a few. SLS and MJF: 380 x 284 x 380 mm (15 x 11.2 x 15") on HP MJF, up to about 700 x 380 x 580 mm (28 x 15 x 23") on large SLS machines. SLA: 150-350 mm (6-14") on desktop and mid-size machines, up to about 1,500 x 750 x 550 mm (59 x 30 x 22") on the largest large-frame machines. FDM: 914 x 610 x 914 mm (36 x 24 x 36") on the largest common industrial machines; bigger parts are printed in sections and bonded. |
| Surface finish | As-printed: SLA 1-4 µm Ra (40-160 µin), the smoothest; MJF 5-10 µm Ra (200-400 µin) and SLS 8-15 µm Ra (315-600 µin) after bead blasting; metal LPBF 6-15 µm Ra (240-600 µin) on vertical walls and rougher on supported faces; FDM 10-25 µm Ra (400-1,000 µin) with visible layer lines. Sanding and painting, vapor smoothing, tumbling, or machining the critical faces brings any of them to 0.8-1.6 µm Ra (32-63 µin) or better. |
| Lead time | Polymer prototypes in 2-5 business days (SLA and FDM often next day); SLS and MJF batches in 3-7 business days; metal parts in 1-3 weeks as-built and 3-6 weeks with HIP, heat treatment and machining. Production lead time depends on process qualification as much as on printer time. |
Typical of U.S. job shops; confirm with the shop for your part.
Materials
Polymers: FDM prints PLA, ABS, ASA, PETG, nylon and polycarbonate, and on heated-chamber industrial machines Ultem 9085, Ultem 1010 and PEEK. SLA prints photopolymer resins that imitate ABS, polypropylene, polycarbonate or clear acrylic but are thermosets, not those plastics. SLS and MJF print nylon 12 (PA12), nylon 11 (PA11), glass- and carbon-filled nylon, TPU and polypropylene; printed nylons are PA12 or PA11, not the nylon 6/6 of machined stock. Metals: laser powder bed fusion prints Ti-6Al-4V, 316L and 17-4 PH stainless, Inconel 718 and 625, cobalt-chrome, maraging steel and copper alloys. Aluminum prints as the casting-type alloy AlSi10Mg, because 6061 and 7075 crack as they solidify. Free-machining grades, most wrought aluminum alloys and high-carbon tool steels are not printed.
What drives the cost
- Machine time: build height (layer count) in powder-bed and resin processes, deposited volume in FDM
- Material: metal powder, PEEK and Ultem filament and specialty resins cost several times commodity grades
- Supports and their removal, which is hand labor and dominates the cost of small metal parts
- Post-processing: stress relief, HIP, heat treatment, machining, dyeing, smoothing and painting
- Nesting: how many parts share one build, the biggest lever on SLS, MJF and metal pricing
- Tolerances and finishes the process cannot hold as-printed, which add a machining or finishing step
- Documentation: material certs, build records, witness coupons, CT scans, first article inspection
When to use it
- Prototypes needed in days, before committing to tooling
- Low volumes, from one to a few thousand, where a mold, die or casting pattern cannot be amortized
- Internal channels, lattices, organic shapes and consolidated assemblies that cannot be machined or molded in one piece
- Jigs, fixtures, gauges and end-of-arm tooling for the shop floor
- Spare parts for equipment whose original tooling no longer exists
When not to
- Simple prismatic parts a mill can cut in one or two setups: machining is usually cheaper and more accurate
- Volumes in the thousands and up: injection molding, die casting or stamping cost far less per part
- Tolerances tighter than ±0.1 mm (±0.004") across the part, unless the budget includes post-machining
- Large, flat, thin parts, which warp in every printing process
- Safety-critical or fatigue-loaded parts without a qualified process, HIP where it applies, and an inspection plan
Design tips
- Name the process and material on the RFQ (MJF PA12, SLA clear resin, LPBF Ti-6Al-4V); price and properties differ several-fold between them.
- Send a STEP file for the geometry and a PDF drawing for the features that matter; the drawing carries tolerances, threads and finishes the model cannot.
- Mark critical faces and datums, and leave machining stock on any feature that needs better than the process holds.
- Keep walls at least 1 mm (0.040") thick in polymer and 0.8-1 mm (0.030-0.040") in metal, and avoid large flat areas.
- Add escape holes to hollow sections in powder and resin processes so unfused material can be removed.
- Say which surfaces are cosmetic so the shop orients them up and away from supports.
- Design for the build direction: in SLA, FDM and metal, down-facing surfaces at less than about 45° to horizontal need supports.
Frequently asked questions
- Which 3D printing process should I use?
- Start from the job. SLA for detailed, smooth, cosmetic or clear prototypes. FDM for large, inexpensive prototypes and shop fixtures, or for Ultem and PEEK. SLS or MJF nylon for functional plastic parts from one to a few thousand. Metal LPBF for dense metal parts with internal features. If a mill can cut the part in one or two setups, get a machining quote too.
- How much does 3D printing cost?
- As a rough guide for a palm-sized part from a U.S. shop: FDM and SLA $25-150 each; SLS or MJF nylon $20-100 as a single piece and much less when the build is full; metal LPBF $400-3,000 depending on alloy, supports and post-processing. Size, material and finishing move the price more than anything else. The Noramark cost estimator gives a ballpark from size, material and quantity.
- How accurate is 3D printing?
- For small parts, SLA and metal LPBF hold about ±0.1 mm (±0.004"), industrial FDM ±0.13-0.25 mm (±0.005-0.010") and SLS or MJF about ±0.3 mm (±0.012"), with the error growing on larger parts. Bores, sealing faces and threads that need better are printed oversize and machined.
- Is 3D printing cheaper than injection molding?
- For a few parts, yes, because there is no mold to pay for. For small nylon parts, SLS or MJF usually stays competitive into the hundreds or low thousands; past that, a mold costing from a few thousand dollars upward pays for itself. The crossover moves with part size and complexity, so quote both once the design is stable.
